While Donald Trump was visiting the border area separating San Diego and Tijuana, at the other end of the border, US officials kept to their daily monitoring tasks along the Rio Grande, in Texas.

This river, marking the border between Mexico and the US, is very narrow in certain areas and can be easily crossed on small rafts, leading Border Patrol agents in McAllen and Roma, Texas, to detain and process numerous undocumented migrants Tuesday, as they regularly do.

Back in California, Trump insisted Tuesday that he wants the border wall separating both nations to be as tall as possible and for it to be “see-through,” because “you have to know what’s on the other side of the wall.”

Trump said tall walls were necessary to keep out “incredible climbers,” adding that “they can’t climb some of these walls, some of them they can,” referring to the prototypes he was inspecting.

In his opinion, “the border wall is truly our first line of defense,” claiming that it “will save hundreds of billions of dollars, many, many times what it’s going to cost.”

Trump has promised that Mexico will pay for the controversial wall, something the Mexican government has categorically denied, and has now claimed that the monumental project will be cost effective.